Alternate costume:
Press Up(2), Down(2), Left, Right, Left, Right, B, A at the "Press Start" screen. Wolverine say something to confirm correct code entry. The new costume allows you to heal quicker.

Level	Location	Password
2	Downtown	Wolverine's head, Wolverine's claws, X-Men sign, Wolverine's body
3	Downtown	Wolverine's claws, Sabrewolf, Wolverine's body, Wolverine's head
4	Tokyo	Skull, Wolverines head, X-Men sign, Wolverine's claws
8	Lab	Claw, Blue Head, X-Men sign, Skull
9	Lab	Skull, X-Men sign, Wolverine's claw, Sabrewolf
End		Blue Head, Skull, X-Men sign, Lady

Hint: Enemies:
Duck when the ninjas throw their shuriken. When the staff members have their backs towards you, punch them.